1. CIRES at the University of Colorado and NOAA's National Geophysical Data Center; 325 Broadway,; Boulder; Colorado; 80305-3328; USA
2. Goddard Space Flight Center; Greenbelt; Maryland; 20770; USA
3. GETECH; University of Leeds; LS2 9JT; Leeds; UK
4. Department of Geology; Southern Illinois University; Mail Stop 4324,; Carbondale; Illinois; 62901; USA